Cam-lever actuated, self-adjusting slidable jaw wrench



F. E. ISRAEL March 25, 1958 CAM-LEVER ACTUATED, SELF-ADJUSTING SLIDABLE JAW WRENCH Filed Aug. 27, 1956 5 Sheets-Sheet 1 INVEN TOR ISRAEL FLOYD E.

BY /V.'77.

ATTORNEYS CAM-LEVER ACTUATED, SELF-ADJUSTING SLIDABLE JAW WRENCH Filed Aug. 27, 1956 F. E. ISRAEL March 25, 1958 5 Sheets-Sheet 2 I'NVENTOR E. ISRAEL FLOYD ATTQRNEYS F. E. ISRAEL 7 2,827,814

March 25, 1958 CAM-LEVER ACTUATED, SELF-ADJUSTING SLIDA-BLE JAW WRENCH Filed Aug. 27. less 3 Sheets-Sheet 3 F/G. l0

INVENT OR FLUYD E. BSRAEL g/55mm? ATTORNEYS United tates Patent CAM-LEVER ACTUATEE, SELF-ADJUSTING SLZDABLE HAW WRENCH Floyd E. lsrael, fiutchinson, Kans.

Application August 27, 1956, Serial No. 6136,244-

12 (Claims. (Cl. 81123) This invention relates to wrenches of the self adjusting type in which the jaws close upon the nut, pipe or other work by spring action; and it resides in the new presetting and locking mechanism for such wrenches, particularly those of the crescent type.

The primary object of the invention is to speed and ease the operation of the adjusting and locking mechanisms of adjustable wrenches.

Another object is to provide an improved wrench in which a squeezing action of one hand releases the looking mechanism and opens the jaws so that when the jaws are slipped astride a nut or pipe and the hand pressure is released, the spring action snaps the jaws on the nut or pipe and sets the locking mechanism.

Another object is to provide a locking mechanism which operates on a wedging principle, the wedging being preferably accomplished by the combination of two cams.

Another object is to provide an improved cam locking mechanism which connects the two jaws and effectively prevents their opening a ter the initial setting.

'Anothelhobject is to provide a wrench of this character in which the adjusting elements consist of at least one lever to release the locking mechanism and open the jaws and spring means to close the jaws on the nut or pipe and set the locking mechanism, the initial movemerit of the release lever exerting a powerful disengaging force on the locking elements thereby separating them and permitting a minimum of effort in opening the jaws. Another object is to provide an improved wrench in which the above mentioned mechanisms will automatically readjust the jaws should the initial adjustment be too wide, since the locking elements oppose only the opening of the jaws and so permit the spring means to tighten the jaws on the work should this be necessary. Such a situation would arise in case the jaws were closed across the corners of a nut. As soon as the wrench was moved so the jaws could close across the flats, the mechanism would make this adjustment automatically. This feature also affords a semi ratchet action, since a light pressure on the release lever permits the wrench to be reset without removal from the work.

With the above and other objects and advantages in view, the invention resides in the novel combinations and arrangements of parts and the novel features of construction hereinafter described and claimed, and illustrated in the accompanying drawings which show the present preferred embodiment of the invention. 7

in the drawings;

Pig. 1 is a side elevation of the wrench with the jaws in a partially open position;

Fig. 2 is alongitndinal sectional view showing the jaws in a substantially fully open position, parts being broken away; 7

Fig. 3 is a bottom edge view of Fig. 2;

Fig. 4 is a view similar to Fig. 2 showing the jaws in closed position; V V

Fig. 5 is a detailed and somewhat diagrammatic view 'ice showing the positions of the cams and hand lever when the jaws are closed and the wrench is not in use;

Fig. 6 is a view similar to Fig. 5 showing the positions of these parts after sufiicient pressure has been applied to the hand lever to unlock the cams but not snfiicient to open the jaws;

Fig. 7 is a view similar to Fig. 5 showing the positions of the parts when the jaws are in a mid-open position with the cams in locking engagement;

Fig. 8 is a view similar to Fig. 7 showing the cams unlocked;

Fig. 9 is a view similar to Figs. 5 and 7 but showing the positions of the parts when the jaws are wide open;

Fig. 10 is a view similar to Fig. 9 showing the cams in released or unlocked position;

Fig. 11 is a diagrammatic view to explain the locking action of the cams;

Fig. 12 is a side elevation of one of the pivot pins; and

Fig. 13 is a detail section taken on line 1313 in Fig. 2.

Referring more in detail to the drawings the numeral 1% denotes the wrench body or handle which has at its rear a suitable hand grip portion 11 while its front or outer portion is laterally enlarged and transversely widened as will be seen on reference to Figs. 1, 3 and 4. The widened portion is formed with a longitudinal slot 12 to provide two parallel side plates 13, the forward ends of which are united by a fixed jaw 14. A co acting movable jaw 15 is mounted to slide toward and from the handle carried jaw, and it has a reduced fiat shank 16 to slide between the flat opposed faces of the plates 13 at the front of the slot 12. To guide the movable jaw the plates 13 may be formed with opposed guide channels 17 which extend at right angles to the gripping face of the fixed jaw 14 and which receive ribs 18 formed on opposite sides of the shank 16.

The movable jaw 15 is spring actuated toward the med jaw and is manually moved to an open position by a rotary member 2%} in the intermediate portion of the slot 12. The equivalent of a rack and pinion connection is provided between the member 20 and the jaw 15, and the spring for moving the latter is preferably connected between the rotary member and the handle. As shown, the member 20 comprises a plate having a hub portion 21 rotatable on a pivot 22 extending between the plates 13 and preferably in the form of a cylindrical pin, as shown in Fig. 12. The plates, as seen in Fig. 13, have openings to receive the pivot pin and one of them is screw threaded to receive screw threads 23 at one end of the pin, its other end having a screw driver kerf. The rotary member or plate 20 has a portion extending laterally from its hub 21 and formed with a spiral cam edge 24. The member also has a thinner portion formed with two projections or arms 25 and 26 which extend radially from its hub 21. The thin portion is shown in Fig. 13. The arm 25 carries a pivot 28 for an actuating lever hereinafter described. The other arm 26 is shaped to operate in a notch 29 formed in the movable jaw shank 16, and thus provide the above mentioned rack and pinion connection so that the jaw 15 will be moved when the rotary member 21) is actuated.

Because of its cam edge 24 the member 20 will be termed a cam. It is rotated in one direction by the lever connected to the pivot pin 28 and in the other direction by suitable spring means. The latter is preferably a coil spring 39 disposed along a portion of the hub 21 and having at one end a hook detachably engaged with an aperture 31 in the rotary plate or cam 20, and at its other end a hook detachably engaged with an anchoring pin 32 extending transversely between the plates 13.

. Coacting with theedge 24 of the cam 20 is a shiftable, manually retractable, locking member which might be a slidable wedge or a second rotary cam. As shown,

this cam locking member is a rotary cam designated as a whole by the numeral 35. it is disposed in the rear part of the 'slot 12 and it also comprises a plate with 'a hub portion 36 rotatable on a pivot pin 37. The latter is mounted in the plates .13 and is of the same construction as the pivot pin 22. 'This rotary cam plate has a thick portion extending laterally from its hub and formed with a spiral cam edge 38; and it also has a thin radially projecting portion 39 in which is formed an elongated opening or slot 43. It will be noted that the spirals 24 and 38 of the tw cams are of opposite hand, and that the companion or secondary cam 35 engages the primary cam 20 when they are in locking position to prevent the movable jaw from moving away from the fixed jaw 14. Another important feature of the camassembly is that'the diameters of the stationary pins 22 and 37, about which the cams rotate, are as large as other design conditions permit,

thus providing the maximum frictional resistance or braking on the cams when they are under strain. The cam 35 is biased toward its locking engagement with cam by spring means which may take various forms. I preferably employ a coil spring 41 which extends along a portion of the hub 36 and has at one end a hook detachably engaged in a hole 42 in the cam 35, and at its other end ,a hook'detachably engaged with an anchoring eye 43 suitably fixed to an edge of the wrench handle.

Fig. 4'shows the wrench jaws closed and the cams 20, 35 in locking engagement. Before the jaw 15 can be moved cam 35 must be moved very slightly to release cam 20, as seen in Fig. 6. To do that and to then rotate cam 20 to open the jaw 15 I preferably provide the single hand lever 45 referred to above. This lever has three arms 46, 47 and 48. Ann 46 is relatively long and is forked to straddle the thin portion of the cam 20, being mounted on the pivot pin 28. Arm 47 is relatively short and is also forked to straddle the thin portion 39 of the other cam. This arm 47 carries a bearing pin 49 for a roller 50 disposed to move freely in the slot 40. The 'third arm.48 projects in an outward and rearward direction from the lower edge of the wrench handle and serves as a finger piece. The outer or lower edge of the lever 45 is so shaped that when the enlarged portion of the body 10 is grasped in the hand, the fingers extend around the lever, and when these parts are squeezed the lever will be first moved laterally to a very slight extent swinging cam 20, as will be understood upon reference to Figs. 2 and 4.

The operation of the cams will be better understood 7 on reference to Figs. 5 through 10. Fig. 5 shows the positions of the parts when the jaws are closed, that is, when end S of the slot 40 and sets up a thrust against the right hand side 51 of the slot. Since cam20 cannot move any further in the clockwise direction, the cam 35 must start rotating in a counter clockwise direction. The

force of the spring 41 is overcome by the thrust from the; roller and the latter will move until it reachesS',

" engagement of the cams at all positions, but in most cases"- thus separating the cams as seen in Fig. 6. From this stage through Fig. 8 to Fig. 10, the lever acts simply as a link to pull the primary cam 20 around as the secondary cam 35 continues to rotate in a counter clockwise direc: tion. The action of cam 35 in this movement may be thought of as a simple rocker arm indicated by the broken line r in Figs. 6 and 10. For this action to be accomplished the broken line z in Fig. 10, which is perpendicu- In actual practice, whether the roller goes as far as the end S of the slot depends on the direction of opening force A, relative strength of the primary and secondary springs 34) and 41, and friction of the various parts. If spring 30 is considerably stronger, as it should be, than spring 41, the manual force is applied as shown in Fig. 6; and if friction conditions are normal, the roller'will go as far as S before cam 20 starts to move. As above noted Fig. 6 shows the initial movement to separate or unlock the cams, and continued pressure on the lever will cause cam 20 to open the jaws, Figs. 7 and 8 showing the positions of the cams, locked and unlocked respective 41 has been designated weaker, the essential condition is that the closing torque of spring 30 on cam 20 be sufficient to close the jaws in spite of any friction between i the cams caused by the action of spring 41 on cam 35. in the actual design of the wrench the exact relative strength of the springs depends on the length of their lever arms, friction between the cams, etc.

The closing cycle is as follows. Assume the jaws have been opened Wide to put the cams in the position shown in Fig-10, and that a nut about the size of the jaw opening has been slipped between the jaws, and finally all manual pressure A is withdrawn. Then the only actuating forces must be in the two springs and they start revolving their cams in a clockwise direction as indicated by the arrows on the cams in Fig. 5. When the movable jaw strikes the nut, the primary cam 20 will cease to rotate, and the secondary cam 35 will continue to rotate until it contacts the primary cam 20. When the latter stops rotating, the location of pin 28 is fixed, and a thrust, indicated by the arrow T in Fig. 5, will be given to the lever roller 50 by the side of the slot in cam 35. When that thrust occurs the roller travels toward the other end S of the slot and the lever swings about pin 28 in a clockwise direction. The distance which the roller travels toward S depends upon the jaw position. Figs. 5 and 7 show the finish of the closing cycle for closed and midopen positions respectively.

' 'It is to be noted that the slot in the secondary cam is inclined to the cam radius at the end of the slot. The slot and its inclination are not only to provide proper cam 20 there is a corresponding position of the secondary cam 35'so as to maintain their contact as they are rotated by the hand lever. As above noted the cams are of opposite hand, and they are so proportioned thatall the force transmitted by the movable jaw through the primary cam to the secondary cam, is finally transmitted to the pin 37 of the secondary cam. Hence there is no .backing outf of the secondary cam. As the hand leverv is pressed, the roller 50, or its equivalent, moves along the cam-like slot wall or shoulder 51 causing the cam edges 38 and 24 to move in contact as the two springs are further stressed, but when there is a workpiece between the jaws and pressure on the hand lever is released,

the gripping of the jaws on the work piece will stop further movement of the cam under the action of its spring and the cam will be held in locking engagement with it by the spring 41.

In order to show how the locking action of the cams is accomplished, the diagram shown in Fig. 11 is to be considered in connection with the following formula:

This formula is based on the principles of friction and movements, where:

The opening force R" is given by the following formula: R"=R cos e, where e is the angle between R and R.

For the locking action to be accomplished, available force W must be at least equal to R". In practice W should exceed R in order to provide for any accidental reduction of coefiicient of friction, by oil, etc.

It is apparent from the above formulas and Fig. 11 that a number of sizes and shapes of cams will accomplish the locking action. However in addition to the locking action there must be considered the permissible pressure at contact of cams, ease of release after being strained and jaw-opening movement of cams when strained. Excessive pressure, difiicult release and excessive jaw-opening will occur if actuating arm of primary cam is too long, if the gradients of the cams are too fine and if the cams are too small. Difiicult release and excessive jaw-opening will also occur if cams and pins are not properly hardened. The optimum design for a given wrench can be worked out by application of methematics and mechanics.

Segments of Archimedean spirals are the simplest contours for these cams. The polar equation for such a spiral for the primary cam is:

=-ei where: p=Radius vector. e=Vectorial angle. i=Gradient or variation of p with change of e.

It is apparent that the radius vectors vary uniformly throughout the segment. The equation for the secondary cam is the same type but of opposite sign (opposite hand). A different gradient, 1', may be used if design conditions require it.

To establish the suitability of a given combination of cams it is necessary at the outset to find their contact line (T on Fig. 11) and slope at contact. These may be found most simply by a combined use of large scale models and mathematics.

The manipulation of the wrench is simple and quick. A squeezing action of one hand releases the cam locking mechanism and opens the jaws. The jaws are then slipped astride the nut or pipe and the hand pressure is relinquished. The spring action snaps the jaws on the nut or pipe and sets the locking mechanism. The wrench has many advantages. It completely operable by one hand and has automatic setting not only of the jaws but of the locking elements. By a single motion the locking elements are released, the jaws opened and the locking elements are positioned for instant locking when the pressure is released. There is a minimum of lost :motion since torque is applied to the work instantly upon movement of the wrench handle and no auxiliary :lever is necessary to lock or hold the movable jaw. The use of the dual-cam locking unit along with a single wrench handle provides extreme compactness. The use of a pair of cams, one of which has an arm engaging the movable jaw, permits of comparatively long travel ofthe movable jaw without necessitating large cams or excessive motion a of them. Hence the wrench 'has a wide range of :jaw

opening with minimum bulk in the wrench. Also any heavy strain originating in the locking mechanism is transmitted to the handle and none of this force reaches .the guide for the movable jaw. Further the arrangement of parts is such that crushing action on the work is minimized since the locking element simply opposes the opening force, and no extra force is added to the normal torque of the wrench. It will be apparent from the above that the wrench not only saves time and efifort where the work is readily accessible and visible, but even more so where the work is in cramped quarters and invisible.

From the foregoing, taken in connection with the accompanying drawing, it will be seen that novel and advantageous provision has been made for carrying out the objects of the invention, and while preferences have been disclosed, attention is invited to the possibility of making variations within the scope of the invention as claimed.

I claim:

1. In a wrench having a handle carrying a fixed jaw, a coacting jaw movably mounted on the handle, a cam with a spiral edge rotatably mounted on the handle and having means to actuate the movable jaw, spring means to rotate the cam and actuate the movable jaw toward the fixed jaw, a shiftable locking element mounted on the handle and coacting with the spiral edge of said cam to lock the latter against opening movement, spring means biasing said locking element for movement in one direction, and manually actuated means associated with both said rotary cam and said locking element to first release the locking engagement of the element with the cam and to then rotate the cam against the pull of its spring means.

2. The structure of claim 1 in which said locking element is a second cam with a spiral edge and of opposite hand to the first mentioned cam.

3. The structure of claim 2 in which said manually actuated means is a hand lever disposed along the handle and provided with a pivotal connection with said first mentioned cam and a sliding and pivoted connection with said second cam.

4. The structure of claim 2 in which said spring-actuated second cam has a slot which is inclined to the cam radius at the end of the slot, and in which said manually actuated means is a hand lever disposed along the handle and provided with long and short arms, said long arm having a pivotal connection with said first mentioned cam and said short arm carrying a roller to operate in said slot in the second cam.

5. In a wrench having fixed and movable jaws mounted on a handle, the combination of a rotatable primary cam with a spiral edge and having an arm to engage and actuate the movable jaw, and a rotatable secondary cam with a spiral edge to contact the spiral of the primary earn and lock the movable jaw and its actuating cam, said cams being mounted on pivot pins carried by the wrench handle, each of said cams being biased by spring means for movement in one direction.

6. The structure of claim 5 in which said spring means position both cams and set the secondary cam in locking engagement with the primary cam.

7. The structure of claim 6 together with manually shoulder.

actuated means associated with both cams and movable to first release the secondary cam from its locking engagement with the primary cam and to then rotate both cams 'against the pull of said spring means.

8. The structure of claim 5 in which the spring means actuating the primary cam moves the movable jaw to- 'ward its closed position, the spring means which actuates the secondary cam urges its spiral edge into locking contact with the spiral edge of the primary cam, and hand actuated means associated with both cams and movable to first release the locking engagement of the cams and then rotate both cams against the pull of their respective spring means.

9. The structureof claim 8, in which the two cards are of opposite *handand are so proportioned that any contact throughout their range," their radii and slopes in the contact line will be such that the force transmitted by the movable jaw through the primary cam to the secondary cam is finally transmitted to the pin of the secondary, cam to' prevent any.backing-out of the secondary cam.

10. The structure of claims in which said hand actuated means comprises a hand lever having an arm ,pivotally connected to the primary cam, said secondary cam having an inclined shoulder, and said'lever also having a part to thrust'against and slide' along 'said 11. In a self closing wrench having ed and movable Y 8 jaws, a pair of coac'ting primary and secondary rotary cams with spiral edges each spring actuated in onedirection, the primary cam under the action of its spring moving the movable jaw toward its closed position, :the secondary cam under the action of its spring being moved into locking engagement with the primary' cam,' and manually actuated means controlling the movement of the cams against the action of their springs.

12. The structure of claim 11 in which said manually actuated means,'when'operated, causes firstthe.disengagement of thesecondary from the primary cam to unlock the latter and then causes rotation of the primary cam against the pull of its spring to open the wrench ]8.WS.

References Cited in the file of this patent UNITED STATES PATENTS 

